More than 300 class-action lawsuits have been filed related to the Volkswagen emissions scandal, and the Web is filled with ads from law firms asking people to sign up. But Clarence Ditlow, executive director for the Center for Auto Safety, says that "at this point, there is no need for anyone to 'join' a class action." The lawsuits are likely to be consolidated soon, and one U.S. District Court will handle the case. A class-action settlement could be reached from six months to two years after that, says Ditlow. All who meet the definition of the class will be able to participate and file a claim (unless they opt out). Enter your VIN at www.vwdieselinfo.com to see if your car is affected and, if so, to sign up to receive a $500 gift card from Volkswagen, which should not affect your ability to participate in a lawsuit.

For a possible claim, keep your purchase or lease agreement, any related documents and correspondence with Volkswagen, Audi or your dealer, and any receipts for expenses you may try to claim, says Andre Mura, a lawyer with Girard Gibbs in Oakland, Calif., which filed one of the lawsuits. Make sure VW has your current address.

You don't need to sign up with a law firm to collect on a settlement, but a lawyer can help you decide whether to opt out of the class and file your own suit.